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Dynamic of active microorganisms inhabiting a bioleaching industrial heap of low-grade copper sulfide ore monitored by real-time PCR and oligonucleotide prokaryotic acidophile microarray.

ABSTRACT: The bioleaching of metal sulfide has developed into a very important industrial process and understanding the microbial dynamic is key to advancing commercial bioleaching operations. Here we report the first quantitative description of the dynamic of active communities in an industrial bioleaching heap. Acidithiobacillus ferrooxidans was the most abundant during the first part of the leaching cycle, while the abundance of Leptospirillum ferriphilum and Ferroplasma acidiphilum increased with age of the heap. Acidithiobacillus thiooxidans kept constant throughout the leaching cycle, and Firmicutes group showed a low and a patchy distribution in the heap. The Acidiphilium-like bacteria reached their highest abundance corresponding to the amount of autotrophs. The active microorganisms in the leaching system were determined using two RNA-based sensitive techniques. In most cases, the 16S rRNA copy numbers of At. ferrooxidans, L. ferriphilum, At. thiooxidans and F. acidiphilum, was concomitant with the DNA copy numbers, whereas Acidiphilium-like bacteria and some Firmicutes members did not show a clear correlation between 16S rRNA accumulation and DNA copy numbers. However, the prokaryotic acidophile microarray (PAM) analysis showed active members of Alphaproteobacteria in all samples and of Sulfobacillus genus in older ones. Also, new active groups such as Actinobacteria and Acidobacterium genus were detected by PAM. The results suggest that changes during the leaching cycle in chemical and physical conditions, such as pH and Fe(3+)/Fe(2+) ion rate, are primary factors shaping the microbial dynamic in the heap.

SUBMITTER: Remonsellez F

PROVIDER: S-EPMC3815317 | biostudies-literature | 2009 Nov

REPOSITORIES: biostudies-literature

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Dynamic of active microorganisms inhabiting a bioleaching industrial heap of low-grade copper sulfide ore monitored by real-time PCR and oligonucleotide prokaryotic acidophile microarray.

Remonsellez Francisco F Galleguillos Felipe F Moreno-Paz Mercedes M Parro Víctor V Acosta Mauricio M Demergasso Cecilia C

Microbial biotechnology 20090527 6

The bioleaching of metal sulfide has developed into a very important industrial process and understanding the microbial dynamic is key to advancing commercial bioleaching operations. Here we report the first quantitative description of the dynamic of active communities in an industrial bioleaching heap. Acidithiobacillus ferrooxidans was the most abundant during the first part of the leaching cycle, while the abundance of Leptospirillum ferriphilum and Ferroplasma acidiphilum increased with age ...[more]

PMID: 21255296

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Project description:In the actual mining scenario, copper bioleaching, mainly raw mined material known as run-of-mine (ROM) copper bioleaching, is the best alternative for the treatment of marginal resources that are not currently considered part of the profitable reserves because of the cost associated with leading technologies in copper extraction. It is foreseen that bioleaching will play a complementary role in either concentration-as it does in Minera Escondida Ltd. (MEL)-or chloride main leaching plants. In that way, it will be possible to maximize mines with installed solvent-extraction and electrowinning capacities that have not been operative since the depletion of their oxide ores. One of the main obstacles for widening bioleaching technology applications is the lack of knowledge about the key events and the attributes of the technology's critical events at the industrial level and mainly in ROM copper bioleaching industrial operations. It is relevant to assess the bed environment where the bacteria-mineral interaction occurs to learn about the limiting factors determining the leaching rate. Thus, due to inability to accurately determine in-situ key variables, their indirect assessment was evaluated by quantifying microbial metabolic-associated responses. Several candidate marker genes were selected to represent the predominant components of the microbial community inhabiting the industrial heap and the metabolisms involved in microbial responses to changes in the heap environment that affect the process performance. The microbial community's predominant components were Acidithiobacillus ferrooxidans, At. thiooxidans, Leptospirillum ferriphilum, and Sulfobacillus sp. Oxygen reduction, CO2 and N2 fixation/uptake, iron and sulfur oxidation, and response to osmotic stress were the metabolisms selected regarding research results previously reported in the system. After that, qPCR primers for each candidate gene were designed and validated. The expression profile of the selected genes vs. environmental key variables in pure cultures, column-leaching tests, and the industrial bioleaching heap was defined. We presented the results obtained from the industrial validation of the marker genes selected for assessing CO2 and N2 availability, osmotic stress response, as well as ferrous iron and sulfur oxidation activity in the bioleaching heap process of MEL. We demonstrated that molecular markers are useful for assessing limiting factors like nutrients and air supply, and the impact of the quality of recycled solutions. We also learned about the attributes of variables like CO2, ammonium, and sulfate levels that affect the industrial ROM-scale operation.

Project description:The compositions of Octopus Spring and Mushroom Spring (Yellowstone National Park, Wyoming, USA) microbial mats have been thoroughly studied, but the compositions of the effluent waters that flow above the mats have not. In this study, cells in the mats and overflowing waters of both springs were investigated at multiple sites where Synechococcus spp. are the dominant cyanobacteria (ca. 72°C to ca. 50°C), and on several dates. In addition to microscopic analyses of stained and autofluorescent cells, 16S rRNA gene sequencing was used to characterize the major taxa present and a protein-encoding gene (psaA) was sequenced and analyzed by ecotype simulation to predict species of Synechococcus The mats of both springs were similar in terms of the downstream distribution of predominant taxa detected previously. However, waters above these mats were predominated by taxa that reside in upstream mats or communities above the upper-temperature limit of the mat. A disturbance/recolonization study was performed at a site normally predominated by Synechococcus species adapted to low temperatures. After removing indigenous Synechococcus cells, Synechococcus species adapted to higher temperatures, which were predominant in the water overflowing this site, colonized the newly forming mat. Differences in recolonization under reduced and UV-screened irradiance suggested that, in addition to physical transport, environmental conditions likely select for species that are better adapted to these different conditions and can influence mat recovery. A transport model was developed and used to predict that, in Mushroom Spring, erosion predominates in the narrower and deeper upstream effluents and deposition predominates over erosion in wider and shallower downstream effluents.IMPORTANCE In flowing aquatic systems, cell erosion and deposition are important to the dispersal of cells from one location to another. Very little is known about microbial dispersal and the physical processes that underlie it. This study demonstrates its importance to colonization of downstream surfaces and especially to the recolonization and functioning of disturbed sites. Ecological systems in flowing environments are often, roughly speaking, pseudosteady, in that nutrients enter the system and by-products leave at relatively steady rates. Over time, material inputs and outputs must balance. Measurements of input fluxes (e.g., growth rates and proxies, such as photosynthesis rates) are frequent. However, erosion and deposition of cells are seldom measured and ecological significance is sometimes neglected. The importance of these parameters is immediately evident in any attempt to construct a model of long-time community behavior, as spatial ecological structure is significantly impacted and can be dominated by migration of organisms, even in small numbers.

Dataset Information

Dynamic of active microorganisms inhabiting a bioleaching industrial heap of low-grade copper sulfide ore monitored by real-time PCR and oligonucleotide prokaryotic acidophile microarray.

Publications

Dynamic of active microorganisms inhabiting a bioleaching industrial heap of low-grade copper sulfide ore monitored by real-time PCR and oligonucleotide prokaryotic acidophile microarray.

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